/ Spot location for giant rope swing...

This has been playing on my mind for a while now... I'm looking for somewhere that I can rig up a pretty epic ropeswing. I'm from the south west so the closer the better but I would travel for it. I need some where where I can secure the line safely and not get in trouble for doing it. I would also need a ledge or something to jump from. I guess it would depend on the spot as to what gear I would need too but the less the better. Any ideas...

In reply to felixizzy: Im afraid this suggestion isn't particularly great for you.

But the one I plan on doing is under barton bridge. It's over the Manchester ship canal. It's deffo some crazy night time/early morning job. Also there is a motorway that runs over the top of it. There are catwalks that run under the bridge though, access is a little creative (I think there are two ways).